Altered Vascular Endothelium-Dependent Responsiveness in Frail Elderly Patients Recovering from COVID-19 Pneumonia: Preliminary Evidence. - Paneroni, Mara; Pasini, Evasio; Vitacca, Michele; Scalvini, Simonetta; Comini, Laura; Pedrinolla, Anna; Venturelli, Massimo (Journal of Clinical Medicine, 2021)